Norman Cousins was a businessman from the United States who often traveled around the world on business. He enjoyed his __1__ and traveling.

Then, after returning to the United States from a __2__ trip to the Union of Soviet Socialist Republic(USSR), Mr. Cousins got sick. Because he had pushed his body to the __3__ of its strength on the trip, a change began to take place __4__ him. The material between his bones became __5__.